Mounting structure for internal combustion engine on small planing boat

ABSTRACT

Providing a mounting structure for an internal combustion engine on a small planing boat on which an internal combustion engine for driving a jet propulsion pump is mounted, in a boat body between a hull and a deck, with a crankshaft thereof oriented in a front-rear direction of the boat body and on which a cylinder of the internal combustion engine is slantly disposed to one of left and right sides of the boat body, the mounting structure taking a weight balance of the internal combustion engine into account. A distance between an axis of the crankshaft and one mounting bracket arranged on a side where the cylinder of the internal combustion engine is slantly disposed, is longer than a distance between the axis of the crankshaft and the other mounting bracket arranged on the opposite side thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2006-157519 filed on Jun. 6, 2006 the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mounting structure for an internal combustion engine on a small planing boat.

2. Description of Background Art

In the past, in a mounting structure for an internal combustion engine for a small planing boat wherein the cylinders of an internal combustion engine are slantly disposed to the left or right side of the boat body, the conventional engine mounting brackets are provided on both sides of a crankshaft used to be equidistance away from the crankshaft axis. See, for example JP-A No. 2003-26092.

SUMMARY AND OBJECTS OF THE INVENTION

The present invention is aimed at providing a mounting structure for an internal combustion engine for a small planing boat with a weight balance of the internal combustion engine taken into account. It is also an aim of the present invention to provide a mounting structure for an internal combustion engine for a small planing boat, wherein the mounting structure allows the internal combustion engine to be removed with ease through a small removal opening provided in the boat body.

To achieve the above aims, an embodiment of the present invention provides a mounting structure for an internal combustion engine for a small planing boat wherein an internal combustion engine for driving a jet propulsion pump is mounted, in a boat body between a hull and a deck, with a crankshaft thereof oriented in a front-rear direction of the boat body and on which a cylinder of the internal combustion engine is slantly disposed to one of left and right sides of the boat body. A distance between an axis of the crankshaft and one mounting bracket arranged on a side where the cylinder of the internal combustion engine is slantly disposed, is longer than a distance between the axis of the crankshaft and the other mounting bracket arranged on the opposite side thereof.

An embodiment of the present invention provides a mounting structure for an internal combustion engine for a small planing boat wherein an intake port is provided on the side where the cylinder of the internal combustion engine is not slantly disposed.

According to an embodiment of the present invention, the internal combustion engine is balanced weightwise in its lateral direction, so that it can be stably supported.

According to an embodiment of the present invention it is possible to remove the internal combustion engine from the boat body without removing the intake pipe and intake devices connected to the intake port. On the intake side of the internal combustion engine, as compared with the exhaust side, many devices are disposed along with many wires and cables including a throttle wire, so that removing such devices is troublesome. Mounting the internal combustion engine in a laterally inclined position and disposing the intake devices on a more spacious side enables the internal combustion engine to be removed through a small removal opening without removing the intake pipe and intake devices.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a side view of a small planing boat 1 equipped with an internal combustion engine 20 according to the present invention;

FIG. 2 is a plan view of the small planing boat 1;

FIG. 3 is a cross-sectional rear view of the small planing boat 1;

FIG. 4 is a longitudinal cross-sectional view of the internal combustion engine 20 as seen from the left side; and

FIG. 5 is a transversal cross-sectional view of the internal combustion engine 20 as seen from the front.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a side view of a small planing boat 1 equipped with an internal combustion engine 20 according to the present invention. FIG. 2 is a plan view of the small planing boat 1. FIG. 3 is a cross-sectional rear view of the small planing boat 1. The small planing boat 1 is a small saddle-ride type boat. The driver drives the boat straddling a seat 3 on a boat body 2 and gripping a steering handlebar 4 attached with a throttle lever. The boat body 2 is a floating structure which includes a hull 5 and a deck 6 joined together forming an internal space. The internal combustion engine 20 is mounted on the hull 5 inside the space. A jet propulsion pump 7 which is a propulsion means driven by the internal combustion engine 20 is disposed at a rear of the hull 5. As shown in FIG. 1, the jet propulsion pump 7 includes a flow passage leading from a water intake opening 8 formed in the bottom of the boat to a nozzle 9 which is open at the rear end of the boat body 2 and an impeller disposed in the flow passage. The shaft of the impeller is linked to the output shaft of the internal combustion engine 20. The drive rotation speed of the internal combustion engine 20 is controlled by turning the throttle lever attached to the steering handlebar. A nozzle 9 is linked to the handlebar by an operating wire (not shown). Operating the handlebar turns the nozzle 9 for steering so that a track is changed. A stowage space 10 is provided in a front portion of the boat body. A fuel tank 11 is positioned in a longitudinal middle portion of the bottom of the boat body.

FIG. 4 is a longitudinal cross-sectional view of the internal combustion engine 20 as seen from the left side with respect to the forward direction of the boat. In FIG. 4, the arrow F points in the forward direction. FIG. 5 is a transversal cross-sectional view of the internal combustion engine 20 as seen from the front of the boat. In FIG. 5, “V” denotes the vertical plane, passing through the axis of a crankshaft 21, of the boat body 2, “C” the cylinder axis of the internal combustion engine 20, “H” a horizontal plane of the boat body 2, “D” the parting plane (joining plane) between a crankcase 22 and a cylinder block 23 of the internal combustion engine 20, and “HC” the center plane of boat body.

The internal combustion engine is a DOHC, inline four-cylinder, four-cycle engine using a dry sump system with the crankshaft 21 oriented in the front-rear direction of the boat body as shown in FIG. 4. In the present specification, left and right are as seen in the forward direction of the boat. As shown in FIG. 5 (front view), the internal combustion engine 20 is mounted on the hull with its left and right mounting brackets 90 and 91 fixed to mounts 92 and 93 provided on the hull. The cylinder axis C is perpendicular to the parting plane. A cylinder 30, a cylinder head 24, and a head cover 25 are positioned in the direction of the cylinder axis C. An oil pan 26 is also provided in a lower position in the same direction. The cylinder axis C is rightwardly inclined by an angle of θ with respect to the vertical plane V passing through the axis of the crankshaft 21.

As shown in FIG. 5, the crankshaft 21 is rotatably held in the parting plane between the crankcase 22 and the cylinder block 23. A piston 31 reciprocates in the cylinder 30, causing, via a connecting rod 32, the crankshaft 21 to rotate. A combustion chamber 33 facing the top face of the piston 31 is formed inside the cylinder head 24 placed over the cylinder 30. Inside the cylinder head 24, an intake port 34 and an exhaust port 35 each with one end open into the combustion chamber 33 are also formed extendingly on the left and right sides, respectively. The openings into the combustion chamber of the intake port 34 and exhaust port 35 are closed and opened by an intake valve 36 and an exhaust valve 37, respectively. The intake valve 36 and the exhaust valve 37 are opened and closed by being driven by cams 40 and 41 mounted on a cam shaft 38 on the intake side and a cam shaft 39 on the exhaust side, respectively. The intake cam shaft 38 and the exhaust cam shaft 39 are held in the plane where the cylinder head 24 and the head cover 25 are fitted together.

Referring to FIG. 5, a left balancer shaft 42 and a right balancer shaft 43 are rotatably supported on both sides of, and to be parallel with, the crankshaft 21. The left and right balancer shafts 42 and 43 serve to cancel the secondary vibration caused by the vibration of the crankshaft 21. A balancer drive gear 45 is formed on the outer circumferential surface of a frontmost crank web 44 shown in FIG. 4. On the left and right balancer shafts 42 and 43, driven gears 46 and 47 for the left and right balancers are mounted, as shown in FIG. 5, in positions corresponding to the balancer drive gears, respectively. The driven gear 46 on the left balancer shaft 42 is engaged directly with the drive gear 45. The driven gear 47 on the right balancer shaft 43 is engaged with the drive gear 45 via an intermediate gear 49. In this arrangement, as the crankshaft 21 rotates, the left and right balancer shafts 42 and 43 rotate in mutually opposing directions at a rotation speed twice as high as that of the crankshaft 21 based on a predetermined gear ratio relative to the drive gear, thereby serving to cancel the secondary vibration of the crankshaft 21.

Referring to FIG. 5, a starter motor 55 is disposed to the left above the crankshaft 21. A pinion 56 which performs driving when starting the engine is fitted onto the starter motor shaft. It is engaged with the driven gear 54 for a starter on the crankshaft 21 via a double intermediate gear 57 for speed reduction.

Referring to FIG. 4, an oil tank 70 is attached to a front portion of the crankcase 22 and the cylinder block 23 combined. The oil tank 70 includes a tank body 71 and a tank cover 72. The crankshaft 21 extends to project forwardly on the oil tank side. A rotor 51 of an ACG (AC generator) 50 is attached to the forwardly projecting portion 21 a of the crankshaft. The driven gear 54 for the starter is connected to the rear side of the rotor 51 via a one-way clutch 53.

The tank body 71 integrally includes an ACG cover 74 covering a device section 69 which includes the ACG 50 and the driven gear 54 for the starter. The ACG cover 74 thus partitions the oil tank 70 into the device section 69 and an oil section 73. An ACG stator 52 is fixedly bolted in the ACG cover 74. The oil section 73 partitioned by the ACG cover 74 to be outside the device section 69 includes an oil reservoir 81, oil passages, and an oil cooler housing.

A scavenging pump case 75 and a feed pump case 76 are attached, in the mentioned order, to the front of the tank body 71. The tank cover 72 is attached to the front of the tank body 71 such that it covers the pump cases. A pump shaft 77 extending through the scavenging pump case 75 and the feed pump case 76 is disposed to be on an axis extended from the crankshaft 21. The pump shaft 77 is connected to the forwardly projecting portion 21 a of the crankshaft 21 via a shaft coupling 78 inside the ACG cover 74. A scavenging pump 79 coupled to the pump shaft 77 is provided in the scavenging pump case 75. A feed pump 80 coupled to the pump shaft 77 is provided in the feed pump case 76.

Referring to FIG. 4, a rear end portion of the crankshaft 21 rearwardly projects at the rear of the crankcase 22 and the cylinder block 23 combined. A rear end portion of the rearwardly projecting portion 21 b of the crankshaft is connected to an impeller shaft of the jet propulsion pump 7 via a coupling 58. A cam chain chamber 59 is formed inside of the rear wall of the crankcase 22 and the cylinder block 23 combined. A cam chain 63 is stretched between a drive sprocket 60 on the crankshaft 21 and driven sprockets 61 and 62 on the left and right cam shafts 38 and 39 causing the cam shafts 38 and 39 to be rotationally driven by the crankshaft 21.

Referring to FIG. 4, a main oil passage 65 extends, in the front-rear direction, through a lower portion of the crankcase 22. It is an oil passage for oil to lubricate the bearings and other parts of the crankshaft 21. Though not shown in FIG. 4, right and left balancer lubrication oil passages 66 and 67, for oil to lubricate the bearings of the left and right balancer shafts 42 and 43, extend on both sides of, and in parallel with, the main oil passage 65 as shown in FIG. 5. These oil passages extend through the front wall of the crankcase 22 and receive oil discharged from a feed pump 80, described later. A long rectangular opening is formed through the bottom of the crankcase 22. The opening is covered from below by the oil pan 26 attached to the bottom.

Referring to FIG. 5, an exhaust pipe 86 communicated to the exhaust port 35 is provided on the right side of the internal combustion engine. The exhaust pipe 86 is connected to a turbocharger 82 installed behind the internal combustion engine. FIG. 4 shows the turbocharger 82 and an inter-cooler 85 installed behind the internal combustion engine. The turbocharger 82 includes a turbine section 83 and a compressor section 84. In the turbine section 83, the turbine is rotationally driven by exhaust gas discharged from the exhaust pipe 86 via the exhaust port 35 on the right side of the internal combustion engine. In the compressor section 84, the compressor rotates on the same shaft as the turbine compresses air. When air is compressed, its temperature rises, and sending the compressed air into the intake system causes it to expand thereby lowering the intake efficiency. The air compressed by the compressor is therefore sent to intake pipe and intake devices 87 disposed, as shown in FIG. 5, on the left side of the internal combustion engine after being cooled by passing through the inter-cooler 85. The air then enters, together with fuel, the combustion chamber 33 via the intake port 34 to be combusted there.

Referring to FIG. 5, the internal combustion engine is mounted on the hull 5 by having its mounting brackets 90 and 91, provided on its front and rear left and right sides, fixed to mounts 92 and 93 provided in the corresponding positions on the hull 5. Left mounting brackets 90 project on the left side of the crankcase 22. Right mounting brackets 91 project on the right side of the cylinder block 23. These left and right mounting brackets are fixed to the mounts 92 and 93 of the hull 5 on a same horizontal level. The mounts 92 and 93 are provided with vibration insulators 92 a and 93 a, respectively, to insulate the vibration of the internal combustion engine. The internal combustion engine 20 is mounted on the hull 5 by being fixed at four locations using the front mounting brackets and front mounts shown in FIG. 5 and the rear mounting brackets and rear mounts, not shown, that are structured the same as the front ones.

The present embodiment described in detail above brings about the following effects:

The internal combustion engine is balanced weightwise in its lateral direction, so that it can be stably supported.

(2) The internal combustion engine is mounted in an inclined position, intake pipe and intake devices 87 are disposed on a more spacious side of the internal combustion engine, and a distance between the axis of the crankshaft and one mounting bracket which is disposed on an opposite side where the other mounting bracket is slantly disposed is shortened. As a result, it is made possible to remove the internal combustion engine through a small removal opening without removing the intake pipe and intake devices 87.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

1. A mounting structure for an internal combustion engine on a small planing boat for mounting an internal combustion engine for driving a jet propulsion pump, in a boat body between a hull and a deck, with a crankshaft thereof oriented in a front-rear direction of the boat body and on which a cylinder of the internal combustion engine is slantly disposed to one of left and right sides of the boat body, comprising: a distance between an axis of the crankshaft and one mounting bracket arranged on a side where the cylinder of the internal combustion engine is slantly disposed, is longer than a distance between the axis of the crankshaft and the other mounting bracket arranged on the opposite side thereof.
 2. The mounting structure for an internal combustion engine on a small planing boat according to claim 1, wherein an intake port is provided on the side where the cylinder of the internal combustion engine is not slantly disposed.
 3. The mounting structure for an internal combustion engine on a small planing boat according to claim 1, wherein a vertical plane V passes through the axis of the crankshaft and an axis C of the cylinders is displaced at an angle relative to the vertical plane V.
 4. The mounting structure for an internal combustion engine on a small planing boat according to claim 1, wherein the small planing boat includes left and right mounts that are substantially perpendicular to the vertical plane V.
 5. The mounting structure for an internal combustion engine on a small planing boat according to claim 4, and further including left and right mounting brackets secured to respective left and right mounts, said left and right mounting brackets being secured to said internal combustion engine for positioning the internal combustion engine at an angle relative to said left and right mounts.
 6. The mounting structure for an internal combustion engine on a small planing boat according to claim 5, and further including vibration insulators operatively positioned between respective left and right mounts and left and right mounting brackets.
 7. The mounting structure for an internal combustion engine on a small planing boat according to claim 1, wherein mounting the internal combustion engine at an angle enables the internal combustion engine to be removed from the small planing boat without removing an intake pipe or an intake device.
 8. A mounting structure for an internal combustion engine on a planing boat comprising: an internal combustion engine for driving a jet propulsion pump, said internal combustion engine being mounted in a boat body between a hull and a deck; a crankshaft operatively connected to the internal combustion engine, an orientation of the crankshaft being in a front-rear direction of the boat body and on which a cylinder of the internal combustion engine is disposed at an angle to one of left and right sides of the boat body; a distance between an axis of the crankshaft and one mounting bracket arranged on a side where the cylinder of the internal combustion engine is disposed at an angle being longer than a distance between the axis of the crankshaft and the other mounting bracket arranged on the opposite side thereof.
 9. The mounting structure for an internal combustion engine on a planing boat according to claim 8, wherein an intake port is provided on the side where the cylinder of the internal combustion engine is not disposed at an angle.
 10. The mounting structure for an internal combustion engine on a planing boat according to claim 8, wherein a vertical plane V passes through the axis of the crankshaft and an axis C of the cylinders is displaced at an angle relative to the vertical plane V.
 11. The mounting structure for an internal combustion engine on a planing boat according to claim 8, wherein the planing boat includes left and right mounts that are substantially perpendicular to the vertical plane V.
 12. The mounting structure for an internal combustion engine on a planing boat according to claim 11, and further including left and right mounting brackets secured to respective left and right mounts, said left and right mounting brackets being secured to said internal combustion engine for positioning the internal combustion engine at an angle relative to said left and right mounts.
 13. The mounting structure for an internal combustion engine on a planing boat according to claim 12, and further including vibration insulators operatively positioned between respective left and right mounts and left and right mounting brackets.
 14. The mounting structure for an internal combustion engine on a planing boat according to claim 8, wherein mounting the internal combustion engine at an angle enables the internal combustion engine to be removed from the planing boat without removing an intake pipe or an intake device. 